Push-type centrifuge



PUSH-'rinus CENIRIFUGE Ernst Ruegg, Kusnacht, Switzerland, ass'ignorto'Escher Wyss Aktiengesellschaft, Zurich, Switzerland, acorporation of'Switzerland Application May 27, 1957, Serial No. 661,857

Claims priority, application Switzerland June 7,11956 3 Claims.-(Cl.210-`37,6)

This invention relates to a =push-type centrifuge in which a sieve drumand a diverging feed drum .built therein and rotating therewith forfeedingmaterial with which it is charged to the sieve drum, are`axiallynnovable relatively` to one another.

In hitherto known ,constructions of such lpush-type centrifuges, thefunnel-shaped vfeed drumis usually connected to a push-button bymeans ofstays, which bottom serves to convey the charge withinthe sieve drumwhich, together with this bottom, bounds an entrance chamberfor thematerial to be centrifuged. Charging of the material into the feedfunnel usually takes place from the delivery side of the centrifuge .and,the feed funnel diverges away lfrom the `delivery side of thecentrifuge. The outer `end of the feed funnel or a hring mounted on theouter side ofthe feed funnel limits vthe thickness of the layer ofmaterial disposed-in 4the sieve drum.

Constructions are `also known in `which chargingof the material to `becentrifuged takes place ,from `the side `opposite to the delivery end ofthe centrifuge. -In this case the feed `funnel diverges in ithefdeliverydirection and is provided with a sieve cover which permits`predehydration of the charge.

then in the form of a `ring ywhich is fastened directly `to the outerend of the feed funnel Aand is connected `to a boss by means of stays,the boss carrying the pusher ring and the feed `funnel .l and beinglaxially displaceable relative to the sieve ydrum. The feed funnel ,andthe `boss together define a chamber which 4is vopen toward the sievedrum and here again a ring `mounted :on the boss serves as a layerlimitinggrnembcr ,for :thevmaterial which is moving alongfthesieve drum.

In both constructions ,acceleration ,of `.the charge 'mae `terial to theperipheral :speed of the sieve 'drum takes place at least partly in the:chamber "formed by the feed `drum and the push bottom `or :the feed:drum andthe boss carrying the pusher member. Thesextwo .parts are`necessarily vjoined to one .another by ribs .which cross the path ofthe charge material in Y,this chamber. .Even if one ensures that theseribs are :arranged fas Jnear to the rotational axis as possible 1inorder to lkeep their peripheral velocity to a minimum, damage ofthesolid material by virtue of impacts on the material can `not be entirelyavoided. In this connectionitis to "be remembered that, for example, ata speed of 1200 revolutions per minute of the ,centrifugalirunnen fourfastening ribs effect as many as 80 strokes through the material persecond.

lt is true that the layer limiting members which have hitherto alwaysbeen used maintain an even thickness of layer on the sieve drum. everthat these layer limiting members also cause destruction of the solidparticles of the material by scraping the material at the deliverypoints from within the feed drum onto the sieve drum. Since, in View ofthe high centrifugal force in the sieve drum, the charge ma- The ipushermember is nited States Patent O It has been found how- Y a bearing `forthis shaft.

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terial is considerably compressed in the sieve drum, scraping requires asubstantial expenditure of `energy and, apart from the fact that thishas a destructive effecton the solid particles of the material, thisexpendi ture of energy also necessitates a higher power input to 'thecentrifuge.

'When thepropertiesof the producttovbe centrifuged are variable a layer`limiting member could, in some cases, even be detrimental in so farthat the perform- ,ance ofthe centrifugeislimited to a value which couldeasily have been exceeded for the particular product.

`Finally ,the known construction has the further disadvantage that the.arrangement of the washing pipes or sprinklers which are alwaysprovided for the charge material is difficult inthat these cannot beinserted in the centrifugal drum to the desired depth.

The invention `airns to overcome these disadvantages. In a push-typecentrifuge in which a sieve drum and a feed drum, .diverging inthedelivery direction of the centrifuge, and being built into the sievedrum and rotating therewith for feeding material with which it ischarged to the sieve drum, are axially movable relatively to -oneanotherand ,in which a pusher ring for conveying the charge material within thesieve drum axially thereof, is connected directly to the outer end ofthe `feed `drum and sieve drum. Further, no solid confining wallsareprovided which are formed by ribs, blades vor the like transverselyof the charge material. The ,entrant charge material ows along thesurface of the feed drum and is accelerated only by friction at the in-.ner face of the drum. Thus, all impacts on the charge are avoided. Onthe inside the charge material moving over the feed drum and the sievedrum has a free surface and thus any rubbing of a fixed part on thecharge material pressed within the sieve drum is avoided.

An example of the invention is illustrated in simplified form in thedrawing in which:

Figure l is an axial section of the centrifuge and Figure 2 is a sectionalong the line II--II in Figure 1. -In fa housing 1, a sieve drum 2 isconnected with one end `to the4 outer circumference of a boss 3 which ismounted to overhang on a hollow shaft 4. 5 indicates A conical disc 8 ismounted `on the freerprojecting end of a central shaft 6 arranged withinthe hollow shaft i coaxially therewith, the shaft A 6 being forced torotate together with the shaft 4 by meansof a key 7 but vbeingdisplaceable axially thereof.

The conical Vdisc is disposed within the sieve drum 2. At its outermarginal portion there `is detachably connected a feed drum 9 whichdiverges in the delivery direction-of the centrifuge, i. e. toward thefree open end .of the sievedrum 2, which is remotefrom the shaft. The

`feed'drum has a frusto-.conical shape. `A pusher ring lll), having itsouter circumference in close proximity tothe `inner surface :of thesieve drum, is connected directly to ,theouter endof thefeed .drum 9,the, pusher ring serving Y open end thereof. Its discharge opening isdirected toward the inner surface of the feed drum 9; It lies near 3 theinner end thereof and is arranged approximately tangentially of the drum9 as shown in Figure 2. By virtue of the friction between the chargematerial and the feed drum 9, the material which leaves the conduit 11is carried along by the rotating feed drum. The material rapidly movesoutwards along the inner face of the feed drum which diverges toward thesieve drum and then reaches the inner face of the sieve drum to form alayer l2 (Figure l) on the sieve cover thereof. For the sake ofillustrating the pusher ring liti clearly, the layer of material is notshown in Figure 2.

Upon axial reciprocatory movement of the central shaft 6 and the feeddrum 9 and the pusher ring 10 in relation to the sieve drum 2 the layerof material deposited o-n the latter is gradually moved toward thedelivery side and is finally delivered to a collecting chamber i3 of thehousing. A delivery pipe 14 is provided to supply washing liquor intothe sieve drum 2.

No solid walls are provided inside of the feed drum 9 andthe sieve drum2 with which the layer of material moving within these drums could comeinto contact. A free space of suflicient width is left adjacent theinner surfaces of the feed drum 9 and the sieve drum 2 so as to allowthe material to move within said drums while having a free surfacetoward the inside. The disc boss S which supports and drives the rotaryfeed device comprising feed drum 9 and pusher ring it) is connected withsaid feed device in a region outside the surface of the feed drum andpusher ring over which the material to be centrifuged travels,.so'thatno stays or blades cross the layer of material which could'have animpact eifect on the material which is accelerated during rotation ofthe feed drum. The solid particles are therefore considerably protectedduring treatment in this centrifuge.

Assuming that the pusher ring and feed drum are moved to and frorelative to the sieve drum by a distance a, that is to say from aposition as illustrated to one indicated by the chain -dotted lines, inthe centrifuge as described above an even layer of Ymaterial is nolonger formed even if the material enters continuously. Instead, theinner upper face of the layer in the sieve drum will have a wave shapewith a wave length a because during each forward movement of the pusherring the material is heaped up. During the return movement of the pusherring the crest and trough of the wave is somewhat balanced by virtue ofthe centrifugal force. Experience has shown that despite ythe omissionof a layer limiting member the differences in the thickness of the layerremain within relatively small limits so that this causes nodisadvantages. On the other hand the heaping up of the material in theinlet chamber is no longer limited as in the case of hitherto knownconstructions s'o that the centrifuge can always be charged with anamount Y determined by the efticient centrifuging of the solidparticles. The constructionaccording to the invention has the furtheradvantage that liquid extracted duringrentry does not reachmaterial'which is already located on the sieve face of the sieve drum ascould be the case in known constructions where the liquid alwaysseparates on the delivery sided bounding surfaces of the feed chamber.

Instead of a frusto-.conical feed drum 9 as illustrated it can have theshape of a hollow body of revolution with an inner face having anarchedmeridian curve, either the concave Vor convex side of the meridian curvefacing the axis of rotation.

In order also to protect the material as much as preferably has a smoothinner face.

What is claimed is: l. A push-type centrifuge comprising a sieve drumhaving an open end and being mounted with its opposite Yend to rotateabout an axis, in which sieve drum material'is centrifuged whilebeingconveyed in the axial direction toward said open end; a rotary feeddevice arranged within saidsieve drum coaxially therewith; said rotaryfeed device comprising a feed drum of generally frusto-conical shapediverging in the direction toward the open end of said sieve drum and apusher ring rigidly connected to the peripheral end of said feed drumand having its outer circumference in close proximity to the innersurface of said sieve drum; a stationary feed device for leadingmaterial to be centrifuged into said feed drum, the material therebybeing caused to rotate and to travel along the inner surface of the feeddrum and the pusher ring toward the inner surface of the sieve drum; andsupporting and driving means for said rotary feed device causing saidrotary feed device to rotate with the sieve drum while allowing axialreciprocatory displacement in relation to kone another, said supportingand driving means being connected with said rotary feed device in aregion outside the surface of the feed drum and pusher ring over whichthe material to be centrifuged travels; and inside of the feed drum andthe sieve drum an adjacent free space of sufficient width being left, soas to allow the material to move therein while having a free surfacetoward the inside.

2. The push-type centrifuge defined in claim 1 in which the feed drumhas a smooth inner surface in the region over which the material to becentrifuged travels. Y

3. A push-type centrifuge comprising a hollow rotary shaft, a bossmounted overhung on a free end of said hollowshaft; a sieve drum beingconnected with one end to the outer circumference of said boss andhaving an open free end remote from said shaft; a central shaft arrangedwithin said hollow shaft coaxially therewith and having an end projetingfrom said free end of the hollow shaft; means drivingly interconnectingsaid hollow shaft and said central shaft while allowing axialreciprocatory movement in relation to one another; a

' disc boss mounted on the projecting end of said central shaft withinsaid sieve drum; a feed drum of generally frusto-conical shape arrangedcoaxially with said central shaft and having its inner end fastened onthe peripheral end of said disc boss and diverging toward the open endof the sieve drum; a pusher ring rigidly connected to the outer end ofsaid feed drum and having its outer circumferencein' close proximity tothe inner surface of the sieve drum, so that, with an axialreciprocating movement of the central shaft in relation to the hollowshaft, material to be centrifuged lying in said sieve drum is graduallypushed byV said pusher ring toward the open end of the sieve drum; and astationary feed conduit leading into the interior of the sieve drumthrough the open end thereof and havinga discharge opening directedtoward Vthepinner surface of said feed drum, so that materialdischarging from said feed conduit is caused to rotate with the feeddrum and travels over the inner Vsurface thereof toward the sieve drum;and inside of the -to move therein while having a free surface `towardthe inside. Y

No references cited.V

